The present invention concerns an ancillary apparatus for knee prosthesis.
It is known that knee breaks and/or diseases particularly arthritic diseases are becoming today more frequent, above all, in the increasing sport activities field as in the non-sport practicing population because of age or life lengthening and/or simply greater mobility.
The instruments for knee interventions have seen an enormous expansion and innumerable are the proposals and structures suggested in the literature or applied in hospital practice also, and mainly in the attempt to suggest and finally provide an apparatus of universal character, i.e., able to be applied to the knee in different forms and sizes which knowingly vary from one person to the other.
Among the numerous patents and patent publications, may be mentioned U.S. Pat. Nos. 4,892,093, 5,474,559, 5,749,876, European Patent Publications No. 0538,152, No. 0538,153, No. 0555,003, and French Patents No. 2,664,157, No. 2,679,766, No. 2,629,339, No. 2,681,779.
French Patent No. 2,679,766 discloses a femoral cut device for the correct positioning of prosthesis implants in the femoral and sagittal planes, which however needs several guides of cutting blades of different sizes for prosthesis to adapt to the different articulation sizes: some risks in the correct guide positioning are possible.
The resection apparatus according to French Patent No. 2,664,157 includes a guide for the cutting blades in two blocks, one movable with the bevelling cuts support and one adjustable in height for the anterior cut.
In the PCT-Publication WO96/01588 (corresponding to U.S. Pat. No. 5,749,876 and EP No. 0721314) the apparatus for the knee condyles resection and for the positioning of a prosthesis comprises: a support with an inferior basis; a guide of the blades of the anterior and posterior cuts, either chamfer or not; an intramedullary femoral rod, and tracer or contact means, said guide having three blocks two of which are mobile and adjustable in height; further one of the blocks comprises means to guide one of the anterior, posterior chamfer (or not) cuts, and the other two blocks comprise guide means for the remaining cuts.
There is no doubt that the proposed solutions and devices, above all those according to said U.S. Pat. No. 5,749,876, have merit, however, they are never free of structural complexities which, moreover, involve operative complications; further they have production and running costs which strongly handicap a generalized diffusion.
The first object of the present invention is to provide an instrumentation particularly simple, compact, reliable and universal both in structural and operative terms.
Another object of the invention is to provide adjustment and control means which are decidedly advantageous compared with the corresponding ones of the prior art.
The present invention concerns an ancillary apparatus for knee prosthesis, in particular for guiding the femoral cut blades or saws which permit the insertion of the prosthesis components mostly adapted to the conformation of each patient, said apparatus comprising several blade-guide blocks vertically approached, in this case a first inferior (lower or bottom) block (4) for posterior cut guide, a superior or head block for the anterior cut, two median (intermediate) blocks (2 and 3) for posterior (2), anterior (3) chamfer cuts, and means (5, 6) of support, seal and motion of said blocks.
According to a first feature of the invention the apparatus is characterized in that said anterior and superior (i.e., terminal) blocks are only vertically movable, have at least two vertical holes for the passage of motion means, at least one horizontal hole for the insertion of means complementary to said means and front slits which are inclined to a horizontal line, are remote in respect to the inferior and superior edges of said end blocks; the intermediate blocks move only horizontally, are provided with holes corresponding to the holes and inclined slits on the edges of said intermediate blocks.